Inhibitory effect of D-limonene on proliferation of glioblastoma cells and its mechanism
10.13481/j.1671-587X.20240308
- VernacularTitle:D-柠檬烯对胶质母细胞瘤细胞增殖的抑制作用及其机制
- Author:
Tengfei WANG
1
,
2
;
Feng CHEN
;
Ling QI
;
Ting LEI
;
Meihui SONG
Author Information
1. 大理大学药学院,云南 大理 671000
2. 广州医科大学附属清远医院 广东省清远市人民医院,广东 清远 511500
- Keywords:
D-limonene;
Glioblastoma;
Apoptosis;
Transplantation tumor;
Protein kinase B
- From:
Journal of Jilin University(Medicine Edition)
2024;50(3):647-657
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To discuss the effect of D-limonene on the proliferation and apoptosis of the glioblastoma(GBM)cells,and to clarify its possible mechanism.Methods:The GBM cells were divided into control group(0 mmol·L-1 D-limonene)and 0.2,0.4,0.6,0.8,and 1.0 mmol·L-1 D-limonene groups.CCK-8 method was used to detect the inhibitory rates of proliferation of the cells in various groups;clone formation assay was used to detect the clone formation rates of the cells in various groups;Annexin Ⅴ-FITC/PI method was used to detect the apoptotic rates of the cells in various groups;Western blotting method was used to detect the expression levels of protein kinase B(AKT),B-cell lymphoma-2(Bcl-2),Bcl-2-associated X protein(Bax),and poly adenosine diphosphate(ADP)-ribose polymerase(PARP)proteins in the cells in various groups;imunofluorescence method was used to detect the expression levels of cleaved Caspase-3 protein in the cells in various groups.Fifteen model mice with subcutaneous tumor xenografts were randomly divided into blank group(0 mg·kg-1·d-1 D-limonene),low dose of D-limonene group(200 mg·kg-1·d-1 D-limonene),and high dose of D-limonene group(400 mg·kg-1·d-1 D-limonene),and there were 5 mice in each group.The inhibitory rates of the tumor in vitro in various groups were calculated;HE staining and immunohistochemical staining were used to observe the morphology of subcutaneous tumor tissue of the mice in various groups and the growth curves of the tumor were drawn;immunohistochemical assay was used to detect the positive expression rates of Ki67 protein in subcutaneous tumor tissue of the mice in various groups;TUNEL staining was used to detect the apoptosis of the tumor cells in various groups.Results:In control group,the cells were spindle-shaped,in good condition,growing closely and adherently,with normal organelles and cytoplasm.After treated for 48 h,the cells in 0.6 mmol·L-1 D-limonene group showed reduced volume,intact but more permeable cell membranes,shrunken cytoplasm,internal vacuole structures,and some fragments floating in the solution.The cells in 0.8 and 1.0 mmol·L-1 D-limonene groups exhibited significant apoptotic bodies and were in an apoptotic state.The CCK-8 results showed that compared with control group,the inhibitory rates of proliferation of the U87,LN229,and GL261 cells in 0.6,0.8,and 1.0 mmol·L-1 D-limonene groups were significantly increased(P<0.01),the inhibitory rates of proliferation of the U87 and GL261 cells were significantly increased(P<0.01).The clone formation assay results showed that compared with control group,the clone formation rates of the U87,LN229,and GL261 cells in 0.4,0.6,and 0.8 mmol·L-1 D-limonene groups were significantly decreased(P<0.05 or P<0.01).The AnnexinⅤ-FITC/PI results showed that compared with control group,after treated with D-limonene for 48 h,the apoptotic rates of the LN229 cells in 0.6,0.8,and 1.0 mmol·L-1 D-limonene groups were significantly increased(P<0.01).The Western blotting results showed that compared with control group,the expression levels of Bax proteins in the LN229 cells in 0.6,0.8,and 1.0 mmol·L-1 D-limonene groups were significantly increased(P<0.01),while the expression levels of AKT and Bcl-2 proteins were significantly decreased(P<0.01),the expression level of PARP protein in the LN229 cells in 0.8 and 1.0 mmol·L-1 D-limonene group was significanthy increased(P<0.01).The immunofluorescence results showed that compared with control group,the expression levels of cleaved Caspase-3 protein in the LN229 cells in 0.6,0.8,and 1.0 mmol·L-1 D-limonene groups were significantly increased(P<0.01).Compared with blank group,the tumor volumes of the mice in low and high doses of D-limonene groups were significantly decreased(P<0.01).Compared with blank group,the tumor weights of the mice in low and high doses of D-limonene groups were significantly decreased(P<0.05),and the inhitory rates of tumor were significantly increased(P<0.05).The tumor cells in blank group were diffusely distributed,with deepened nuclear staining and increased nucleocytoplasmic ratio;a large number of degenerated and necrotic tumor cells were observed in tumor tissue of the mice in low and high doses of D-limonene groups.Compared with blank group,the positive expression rates of Ki67 protein in tumor tissue of the mice in low and high doses of D-limonene groups were significantly decreased(P<0.01).Compared with blank group,the apoptotic rates of tumor cells of the mice in low and high doses of D-limonene groups were significantly increased(P<0.01).Conclusion:D-limonene has the inhibitory effect on the proliferation of the GBM cells;its mechanism may be related to the regulation of AKT protein expression and the activation of the Caspase-3 pathway to induce the apoptosis.
